Praying as requested, but with a heart of compassion and understanding, let John know you have boundaries. If you attend a church, invite John along and get him introduced to a bible study group or Sunday school class. Being a part of the body of Christ may fill that void in ways that are impossible for any one person. If you need more help, visit us at Chaplains Office
I pray the Lord will give you the courage to be more assertive with John in explaining your need to spend time with other people, and that he will be understanding of this. In Jesus name.